"That morning I woke up like somebody had sucker-punched me," McGrath said last year. "The only feeling I can describe that's any close to it was the feeling I had after 9/11."

"That's right," the narrator intones. "McGrath compared more than a million Kentuckians who voted for President Trump to terrorists. Amy McGrath is too extreme for Kentucky."

Another ad, called "Difference," draws differences between Roskam, called Illinois' most bipartisan member of Congress, with "partisan" Casten, slamming him for comparing Trump to 9/11 mastermind Osama bin Laden.

"Trump and Osama bin Laden have a tremendous amount in common," Casten said in February, first reported by the Washington Free Beacon.

The narrator then encourages viewers to vote for "bipartisan leadership and civility."

The Cook Political Report rates Roskam's race as leaning Democratic, while it has Barr's as a toss-up.

The nod to civility strikes at one of the central discussions in American politics heading into the midterms on Tuesday.

Republicans have decried liberal "mobs" at the Supreme Court and elsewhere who harass politicians, while Democrats point the finger at Trump as creating the climate for extremists like the supporter of his who mailed explosive devices to more than a dozen prominent White House critics, including Barack Obama and Hillary Clinton.

Many critics of Trump have made extreme comparisons similar to McGrath and Casten. Journalist Julia Ioffe apologized last week after saying Trump had radicalized more people than the Islamic State terrorist group, also known as ISIS.

Author Bruce Bartlett recently tweeted Trump and Adolf Hitler had differences, except there were all positives for Hitler.

Key differences between Donald Trump and Adolph Hitler–Hitler served honorably in the military, Trump didn't; Hitler was faithful to his wife, Trump cheated on all his wives; Hitler wrote a book, Trump's were all ghostwritten.